German Published Patent Application No. 195 21 872 A1 describes a control system for the braking system of a vehicle that is equipped with an electrically controllable braking system. In order to improve the braking behavior of a vehicle consisting of at least two subvehicles (tractor vehicle and trailer or semitrailer), the beginning and/or the end of the braking effect of a subvehicle and of the vehicle combination is determined in order to ascertain, from the difference in the values sensed, correction signals for controlling the trailer or semitrailer. This ensures that the brakes of the two subvehicles are applied at the same time, and are released again at the same time. Actions which allow the detection of an operating mode of the tractor vehicle with and without a trailer are not presented. The procedure set forth above for correcting the trailer or semitrailer braking signal may therefore be performed even if no trailer is present.